了解宇宙是如何运行的（2010）

How the Universe Works S09E02

Part 3 March 16, 2022, 8:54 a.m.

太阳系诞生时的45亿年旅程
trip back in time to
the birth of the solar system.
这颗彗星是太阳系
This comet is a remnant of
自身形成时的残留物
the formation of
the solar system itself.
因此，这是一个打开时间胶囊的机会
So this is an opportunity
to open that time capsule
让我们一睹古代太阳系的风采
and get a view into
the ancient solar system.
67P彗星可以帮助我们回答
Comet 67P
could help us answer one
关于地球的一个最重要的问题
of the most important
questions about our planet.
关于地球的最大的
One of the big mysteries
that we have
谜团之一是水从何而来？
about Earth is where did
the water come from?
今天，水覆盖了地球表面的
Today, water covers
over two-thirds
三分之二的面♥积♥
of the Earth's surface.
但事情并不总是这样的
But it wasn't always that way.
46亿年以前
4.6 billion years ago,
太阳系内部遍布着
the inner solar system formed
from a maelstrom
大量岩石碎片
of rocky debris.
温度非常高
Temperatures were so hot,
早期地球上的水都蒸发掉了
any water on the early Earth
boiled away.
证据告诉我们，地球上的水
What the evidence suggests to
us is that Earth's water arrived
是在地球形成后到达地球的
at Earth after the Earth formed,
而我们认为的主要机制是
and the primary mechanism that
we thought were responsible
彗星
were our comets.
克里斯蒂安森:你必须知道彗星基本上
CHRISTIANSEN: You have to
remember that comets are
就是由冰和灰尘组成的大雪球
basically just big balls
of ice and dirt.
“罗塞塔”任务的主要目标之一
One of the main goals of
the Rosetta mission was
是分♥析♥这颗彗星上的水
to analyze the water
on this comet
看看它是否与地球上的水相匹配
and see if it matched
the water on Earth.
彗星来自太阳系
Comets come from
two regions at
最外♥围♥的两个区域……
the outermost reaches
of our solar system...
奥尔特云
The Oort Cloud
和柯伊伯带
and the Kuiper Belt.
奥卢塞伊:柯伊伯带位于我们太阳系的一个平面上
OLUSEYI: The Kuiper Belt is in
a plane of our solar system,
大多数人都知道的冥王星就在其中
and the member that most
people are aware of is Pluto,
但除此之外，还有一个
but beyond that,
there is a spherical
球形分布的冰体，奥尔特云
distribution of icy bodies,
the Oort Cloud.
沃尔什:这是一个彗星库
WALSH: This is a repository of
comets that extend for
它离太阳的距离
hundreds of thousands of times
比地球到太阳的距离远数十万倍
further away from the sun
than we find the Earth,
它是一种巨大的球状云，围绕着太阳
and it's kind of a big,
spherical cloud around the sun
对于很多大彗星来说，这是一种深度冻结的状态
that's kind of deep freeze for
a bunch of big comets.
数以十亿计的冰冻天体
Billions of icy objects
在太阳系混沌内部的外面
orbit safely beyond the chaos of
安全地运行
the inner solar system,
锁住了原始的水
locking in primordial water.
沃尔什:彗星的寿命很有意思
WALSH: The life span of
a comet is fascinating.
在40多亿年的时间里
They might do absolutely
nothing out there for over
它们可能什么都不做
four billion years
until the right
直到它们的轨道发生了一些的改变
tweak of their orbit or tug
from a planet changes
或者行星的引力改变了一切，突然之间
everything, and all
of a sudden, they're
它们来到了一条通往太阳的道路上
on a path in towards the sun
and that ice that's been in deep
数十亿年来深冻的冰开始升温
freeze for billions of years
starts to heat up.
天文学家认为，67P彗星以前的主场
Astronomers believe that
Comet 67P's former home turf
是柯伊伯带，直到有什么东西
was the Kuiper Belt until
something sent it
把它发射到内部
ricocheting inwards.
谢里丹:木星引力的影响
SHERIDAN: The influence of
the gravity of Jupiter,
因为木星是一个巨大的行星
because Jupiter's such
a massive planet,
实际上是它吸引了彗星，把它拉进了
it actually attracted
the comet and pulled it into
太阳系内部
the inner solar system.
杜尔达:它慢慢地受到扰动
DURDA: It slowly was perturbed
迁移到太阳系内部
and migrated into
the inner solar system,
就是我们今天看到的地方……它在旅行
where we see it today...
It's traveled.
我的意思，并不是，你知道的，在太空中直线的
I mean, not just, you know,
billions of miles in linear
数十亿英里（约16亿公里），而是，我的意思，这真的是……
space, but, I mean, really,
所有你能想像到的成形的轨道
when you think of all
the orbits that must have made,
足足有数万亿英里，那是一个……
just trillions upon trillions
of miles, that's a...
这么小的东西却要走这么远
That's quite a journey for
such a little object.
现在，67P围绕太阳运行的轨道是6.5年
Now, 67P loops around
the sun in a 6.5-year orbit
它的运行距离远至木星
that travels
as far out as Jupiter
近至火星
and closer in than Mars.
当它靠近太阳时，其冻结的冰
As it gets nearer to the sun,
its frozen ice
开始升温，导致了一个著名的效应
begins to heat up,
leading to a famous effect,
彗星的尾巴
the comet's tail.
阳光射进彗星的表面并加热
Sunlight comes in and heats up
the comet's surface,
然后热量转移到彗星内部
and it gets transferred to
the interior, where there's
那里有很多冰，于是冰被加热
a lot of ice,
and the ice gets heated up,
然后冰蒸发并到达彗星表面
and it vaporizes and makes
its way to the surface.
一旦它来到彗星表面，太阳风就会
And once it's sitting on
the surface, the solar wind is
轰击彗星
bombarding that comet,
它会把所有的物质从彗星剥离于是形成了
and it drags all of that
material out into
一条美丽的长尾巴
a long and beautiful tail.
“罗塞塔”飞入其尾部
Rosetta flew
into the tail to
并分♥析♥水蒸气
analyze the water vapor.
即此行的目的……证实
Its goal... confirm it's
the same type
它和地球上的水是同一种类型
of water as we have on Earth.
克里斯蒂安森:水确实有不同的味道
CHRISTIANSEN: Water does come
in different flavors,
我不是指的咸水或淡水
and I don't mean saltwater
or freshwater.
我是说水是由什么组成的，它的分子
I mean what the water's made
of, its molecules.
拜沃特斯:我们讨论的是质子、中子
BYWATERS: We're talking about
the actual, actual chemical
和电子层面上的
makeup on the proton,
实际化学组成
neutron, and electron level,
所以你以前可能听说过重水
so you might have heard
of heavy water before.
意思就是，有一个额外的中子
And that just means that
there is an extra neutron.
沃尔什:虽然也是H20，但是其中一个氢原子
WALSH: It's H20, but one of
the hydrogens
多了一个中子
has an extra neutron,
所以我们叫它氘[dāo]
so we call it deuterium.
所以水实际上比普通水重
And so that water actually
weighs more the normal water
因为在化合物中有额外的中子
because of that extra neutron
in the mix.
在地球上，水的比例大约是